This video is entirely medic although the Warden is available for Heavy Assault, Engineer, and Medic. The warden can be useful if played in certain situations and conditions. Other then that, the gun's DPS doesn't allow for much flexibility when you're caught out or not in control of things. If you got any questions, lemme know.
I used to use this to counter snipe as an engineer, but a semi auto shotgun with slugs does a better job of making them rage tell you, and a better job all round.
